1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
/* Analyze functions to determine if callers need to allocate a frame header
on the stack. The frame header is used by callees to save their arguments.
This optimization is specific to TARGET_OLDABI targets. For TARGET_NEWABI
targets, if a frame header is required, it is allocated by the callee.
Copyright (C) 2015 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "context.h"
#include "coretypes.h"
#include "tree.h"
#include "tree-core.h"
#include "tree-pass.h"
#include "target.h"
#include "target-globals.h"
#include "cfg.h"
#include "cgraph.h"
#include "function.h"
#include "basic-block.h"
#include "gimple.h"
#include "gimple-iterator.h"
#include "gimple-walk.h"
static unsigned int frame_header_opt (void);
namespace {
const pass_data pass_data_ipa_frame_header_opt =
{
IPA_PASS, /* type */
"frame-header-opt", /* name */
OPTGROUP_NONE, /* optinfo_flags */
TV_CGRAPHOPT, /* tv_id */
0, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
0, /* todo_flags_finish */
};
class pass_ipa_frame_header_opt : public ipa_opt_pass_d
{
public:
pass_ipa_frame_header_opt (gcc::context *ctxt)
: ipa_opt_pass_d (pass_data_ipa_frame_header_opt, ctxt,
NULL, /* generate_summary */
NULL, /* write_summary */
NULL, /* read_summary */
NULL, /* write_optimization_summary */
NULL, /* read_optimization_summary */
NULL, /* stmt_fixup */
0, /* function_transform_todo_flags_start */
NULL, /* function_transform */
NULL) /* variable_transform */
{}
/* opt_pass methods: */
virtual bool gate (function *)
{
/* This optimization has no affect if TARGET_NEWABI. If optimize
is not at least 1 then the data needed for the optimization is
not available and nothing will be done anyway. */
return TARGET_OLDABI && flag_frame_header_optimization;
}
virtual unsigned int execute (function *) { return frame_header_opt (); }
}; // class pass_ipa_frame_header_opt
} // anon namespace
static ipa_opt_pass_d *
make_pass_ipa_frame_header_opt (gcc::context *ctxt)
{
return new pass_ipa_frame_header_opt (ctxt);
}
void
mips_register_frame_header_opt (void)
{
opt_pass *p = make_pass_ipa_frame_header_opt (g);
static struct register_pass_info f =
{p, "comdats", 1, PASS_POS_INSERT_AFTER };
register_pass (&f);
}
/* Return true if it is certain that this is a leaf function. False if it is
not a leaf function or if it is impossible to tell. */
static bool
is_leaf_function (function *fn)
{
basic_block bb;
gimple_stmt_iterator gsi;
/* If we do not have a cfg for this function be conservative and assume
it is not a leaf function. */
if (fn->cfg == NULL)
return false;
FOR_EACH_BB_FN (bb, fn)
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
if (is_gimple_call (gsi_stmt (gsi)))
return false;
return true;
}
/* Return true if this function will use the stack space allocated by its
caller or if we cannot determine for certain that it does not. */
static bool
needs_frame_header_p (function *fn)
{
tree t;
if (fn->decl == NULL)
return true;
if (fn->stdarg || !is_leaf_function (fn))
return true;
for (t = DECL_ARGUMENTS (fn->decl); t; t = TREE_CHAIN (t))
{
if (!use_register_for_decl (t))
return true;
}
return false;
}
/* Returns TRUE if the argument stack space allocated by function FN is used.
Returns FALSE if the space is needed or if the need for the space cannot
be determined. */
static bool
callees_functions_use_frame_header (function *fn)
{
basic_block bb;
gimple_stmt_iterator gsi;
gimple *stmt;
tree called_fn_tree;
function *called_fn;
if (fn->cfg == NULL)
return true;
FOR_EACH_BB_FN (bb, fn)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
stmt = gsi_stmt (gsi);
if (is_gimple_call (stmt))
{
called_fn_tree = gimple_call_fndecl (stmt);
if (called_fn_tree != NULL)
{
called_fn = DECL_STRUCT_FUNCTION (called_fn_tree);
if (called_fn == NULL
|| DECL_WEAK (called_fn_tree)
|| !called_fn->machine->does_not_use_frame_header)
return true;
}
else
return true;
}
}
}
return false;
}
/* Scan each function to determine those that need its frame headers. Perform
a second scan to determine if the allocation can be skipped because none of
their callees require the frame header. */
static unsigned int
frame_header_opt ()
{
struct cgraph_node *node;
function *fn;
FOR_EACH_DEFINED_FUNCTION (node)
{
fn = node->get_fun ();
if (fn != NULL)
fn->machine->does_not_use_frame_header = !needs_frame_header_p (fn);
}
FOR_EACH_DEFINED_FUNCTION (node)
{
fn = node->get_fun ();
if (fn != NULL)
fn->machine->optimize_call_stack
= !callees_functions_use_frame_header (fn);
}
return 0;
}
|
